Using pyppeteer to screenshot a Single-Page App

pyppeteer_spa_screenshot_example.py

# How to use pyppeteer to screenshot an SPA
# Joseph Lou & Jérémie Lumbroso, 2021
#
# This example code is hardcoded for https://codepost.io but should
# show how to use pyppeteer for other SPAs 

import asyncio

# ref: https://github.com/miyakogi/pyppeteer/issues/219#issuecomment-563077061
import pyppdf.patch_pyppeteer  # needed to avoid chromium errors
from pyppeteer import launch

LOGIN_URL = "https://codepost.io/login"
TARGET_URL = "https://codepost.io/code/239403/"  # <-- set submission you want to screenshot
JWT_KEY = "eyJ0e..."                             # <-- replace token here

async def main():
    browser = await launch()
    page = await browser.newPage()

    # await page.emulate({
    #   "viewport": {
    #     "width": 500,
    #     "height": 2400,
    #   },
    #   "userAgent": ""
    # })

    # Load a page (any page), to set the local storage (with a Javascript console call)
    # to store the JWT, which subsequent API calls will use

    await page.goto(LOGIN_URL)
    await page.evaluate(f"() => {{ localStorage.setItem('token', '{JWT_KEY}'); }}");
    
    # Load the target page and wait to make sure every it rendered (important for
    # a Single-Page App like codepost.io)
    # ref: https://stackoverflow.com/a/62859172/408734

    await page.goto(
        TARGET_URL,
        {
            "waitUntil" : [
                "load",             # when load event is fired.

                "domcontentloaded", # when the DOMContentLoaded event is fired

                "networkidle0",     # when there are no more than 0 network connections
                                    #    for at least 500 ms

                "networkidle2"      # when there are no more than 2 network connections
                                    #    for at least 500 ms
        ]},
    )
    
    await page.pdf(path="example.pdf")
    await page.screenshot(path="example.png")
    await browser.close()
    print("done")

asyncio.get_event_loop().run_until_complete(main())

Result: